Nanoparticles are nowadays extensively used in many applications in both medical and biomedical sciences such as for drug delivery, for therapy and for diagnostics. For many of these applications, nanoparticles are coated with proteins. Nanoparticles coated with proteins such as antibodies to cancer cells can be used for instance to locate cancer cells in the body. Similarly, for analyte detection in vitro, probes such as antibodies are bound to nanoparticles, whereby binding of the analyte to the antibody on the nanoparticle is detected.
More in particular metal nanoparticles coated with proteins can be used to transduce binding events by changes in their absorption at least in the visible light spectrum. This phenomenon of Localised Surface Plasmon Resonance (LSPR) enables the screening of interactions of biomolecules. Thus, metal nanoparticles coated with proteins can be used in the detection of antibody-ligand interactions, receptor-ligand interactions, enzyme-ligand binding and antibody-antigen association-dissociation kinetics.
Nanoparticles coated with binding partners such as proteins have been described in the art, as well as methods for coating nanoparticles. For instance, US 2010/0029902 describes a method for coating nanoparticles which comprises mixing the nanoparticles and one or more protein types with a dispersed solution, wherein the proteins are adsorbed to entire surfaces of the nanoparticles in order to control and prevent aggregation of the nanoparticles.
A disadvantage of prior art methods is the requirement of high amounts of the binding partner to completely coat the nanoparticles. Often, only low amounts of the binding partner of interest are available.
In addition, as some of these prior art methods result in nanoparticles coated with multiple layers of the binding partner, the interaction of the bound protein with another compound occurs at an increased distance from the surface of the nanoparticle, which affects signal strength in detection methods.
There remains a need in the art to provide methods for coating nanoparticles with binding partners such as proteins wherein only low amounts of the binding partner are required and, for particular embodiments, wherein coating with a single layer of the binding partner can be achieved.